But a week after Susan, 48, arrived in the country with treats for her son, a bemused radio operator called him from the gates of the compound with a message: "Hey, Nick. Your mum's here."
Ms Galleymore, of California, went to Iraq with a feminist peace group, Code Pink, to gather information for a book she plans to write about Iraqi and US parents' views on the war.
But while she was there she decided, despite her son's pleas, to pay him a visit. Piecing together information from his emails and tips from journalists, she tracked him down. "It was as if he was wearing a homing device," she said.
Arriving unannounced and wearing a hijab headscarf, Ms Galleymore approached the soldiers guarding the base.
"I'm coming up behind you, I mean you no harm," she recalled in her weblog. Then she pulled out her US passport. "I have business here and I want to speak to your sergeant."
"Ma'am," the guard said, moving toward her. "Get back in your car, ma'am!"
Ms Galleymore stayed put as six soldiers moved toward her. "I will do that as soon as I talk to your sergeant," she said, and pulled down her hijab.
"You're American," one of the soldiers said. And soon she was inside talking to her son.
"What was most striking was how isolated the solders are," she said. "They're not interacting with the Iraqi people."